package cn.tedu.sp06.fb;

import cn.tedu.web.util.JsonResult;
import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.stereotype.Component;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * 调用商品服务失败时, 执行这里的降级代码, 返回降级结果
 */
@Component
public class ItemFB implements FallbackProvider {
    /**
     * 后台服务调用失败, 应用当前降级类
     * 返回值:
     *      "item-service"  只针对商品服务降级
     *      "*"             对所有后台服务, 都应用当前降级类
     *      null            对所有后台服务, 都应用当前降级类
     * @return
     */
    @Override
    public String getRoute() {
        return "item-service";
    }

    /**
     * 返回给客户端的降级响应数据
     * 封装到 response 对象
     * @param route
     * @param cause
     * @return
     */
    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {
            @Override
            public HttpStatus getStatusCode() throws IOException {
                return HttpStatus.INTERNAL_SERVER_ERROR;
            }

            @Override
            public int getRawStatusCode() throws IOException {
                return HttpStatus.INTERNAL_SERVER_ERROR.value();
            }

            @Override
            public String getStatusText() throws IOException {
                return HttpStatus.INTERNAL_SERVER_ERROR.getReasonPhrase();
            }

            @Override
            public void close() {
                // 用来关闭下面的流
                // BAIS 内存数组流, 不占用底层系统资源, 不需要关闭

                // 文件流, 占用系统文件资源
                // 网络流, 占用网络资源
                // 数据库流, 占用数据库资源
            }

            @Override
            public InputStream getBody() throws IOException {
                // JsonResult --> {code:500, msg:调用后台服务出错, data:null}
                String json = JsonResult
                            .err().code(500).msg("调用后台服务出错").toString();
                // 将 json 封装到 BAIS
                return new ByteArrayInputStream(json.getBytes("UTF-8"));
            }

            @Override
            public HttpHeaders getHeaders() {
                // Content-Type: application/json;charset=UTF-8
                HttpHeaders h = new HttpHeaders();
                h.set("Content-Type", "application/json;charset=UTF-8");
                return h;
            }
        };
    }
}
